In device fabrication, numerous individual integrated circuits, also referred to as chips, are fabricated on a single substrate or wafer. It is also known to form a plurality of multichip modules (MCM's) on a single substrate or wafer. These integrated circuits or MCM's are then separated for individual use. The chips or MCM's are separated by techniques such as dicing, wherein an extremely precise saw is used to separate the individual devices from each other. A dicing saw is one example of an apparatus that is used for dicing substrates into individual chips. One skilled in the art will recognize that other apparatus that are not specifically enumerated herein are also used for this purpose.
Debris is generated during dicing, and the debris is deposited on the diced devices. This debris will adversely affect device performance if it is deposited on certain areas of the device and not removed therefrom. Dicing debris are particularly problematic for devices which are, when in use, spaced from a substrate. An example of such a device is a "flip chip" multichip module, which is illustrated in FIG. 1. The device 20 is affixed to the substrate 10 by, for example, solder bumps 23. Since the bumps 23 have a smaller surface area than the device 20, there is a space 25 between the device 20 and the substrate 10. The space 25 between the silicon chip integrated circuit 20 and the silicon substrate 10 in such a device is typically several mils. If debris becomes lodged in the space 25 during dicing, it can become dislodged during subsequent processing and find its way onto or into a device surface. Once debris is lodged in this space, however, it is difficult to remove using conventional means such as rinsing.
A dicing process in which the device is protected by a polyimide film is disclosed in Japanese Patent Application No. 02-1248 to Kazuyasu Yoneyama. The polyimide coating is applied over the dicing grooves prior to dicing, and removed thereafter. Although the polyimide film prevents the substrate from cracking during the dicing process, the polyimide is difficult to remove. The polyimide film prevents cracks from forming in the substrate near the cut, but, because the polyimide film is deposited over the dicing groove only and is not deposited over the entire surface, it does not prevent dicing debris from accumulating on the uncoated surface of the device.
Japanese Patent Application No. Sho 61 [1986]-96585 describes a process in which a wafer is protected from dicing debris by a coat of photosensitive material that is applied on the wafer prior to dicing. The photosensitive material is described as silicon resin. The photosensitive material is exposed to radiation prior to dicing. The exposed portion of the photosensitive material overlies an electrode on the device. After dicing, the exposed portion of the photosensitive material is removed to provide access to the electrode. The unexposed portion of the photosensitive material is not removed. Consequently, any dicing debris that becomes embedded in the unexposed portion of the photosensitive material during the dicing process is likewise not removed.